This invention relates generally to boxes or containers for produce and the like and to stacking devices or implements for use in carrying, stacking, and palletizing the containers for storage and/or shipment. More particularly, this invention relates to an improved stacking wire for use with lightweight produce containers formed from corrugated paperboard or the like to improve the vertical stacking strength of the containers thereby permitting the containers to be stacked to a considerable height in pallets or the like without fear of collapsing or becoming unstable.
Agricultural produce, such as grapes, strawberries, and the like, is commonly picked in the field and packed directly into relatively flat, open-topped trays or containers which are in turn stacked on pallets at substantial heights for storage and/or shipment to a market for sale. These containers are typically discarded after sale of the produce, whereby the containers are consumed in large numbers during each growing season. As a result, in an effort to reduce the cost of the produce to consumers, the produce containers are frequently formed at least in part from lightweight, folded corrugated paperboard or the like. However, paperboard produce containers do not by themselves have sufficient vertical stacking strength and/or lateral stability to withstand the significant forces encountered when the containers are stacked for storage and/or shipment.
To help prevent crushing of stacked produce containers and resultant destruction of the fragile produce, a variety of devices or implements have been proposed intended to minimize the likelihood of stack instability or collapse during shipment and/or storage. Perhaps the most common of such devices comprises a so-called stacking wire bent to have an inverted generally U-shaped configuration with laterally projecting lower wings for locking reception into a vertical slot defined by a double-layer end or side wall of the container. The stacking wire is sized to project upwardly through a vertical slot defined by the associated side or end wall of another container to provide a convenient carrying device for two containers and further to align with additional pairs of containers in a stack to help maintain the slotted end or side walls in vertical alignment with each other. With this alignment, the double-layer end or side walls of the stacked containers are intended to provide vertical support columns bearing the weight of the stack to help prevent crushing of the individual containers. However, these stacking wires in the past have not been designed to prevent lateral shifting or so-called shoeing in of the double-layer end or side walls, wherein such shifting all too frequently results in misalignment of the support column-forming walls and crushing of the containers and their contents.
Plastic stacking inserts have been proposed to overcome the above-described problems and disadvantages encountered with conventional stacking wires. More particularly, as disclosed in commonly assigned U.S. Pat. No. 4,266,714, plastic stacking inserts have been proposed for reception through the vertical slots in aligned double-layer end or side walls of stacked produce containers to maintain said walls in vertical alignment, wherein the stacking inserts include complementary-shaped interlocking structures such that the stacking inserts define load-bearing support columns supplementing the stacking strength of the aligned end or side walls. However, such plastic stacking inserts are relatively costly in comparison with conventional stacking wires, particularly in view of the fact that the stacking device is normally discarded along with the container after the produce is sold.
There exists, therefore, a significant need for an improved stacking device or implement for use with stacked produce containers and the like to prevent crushing of the containers and their contents during storage and/or shipment, wherein the improved device is both inexpensive to manufacture and easy to install. The present invention fulfills this need and provides further related advantages.